i am looking to go from the beat 350 in my 1970 skylark custom to a fresh 455. right now i guess that the 350 gets me about ten mpg or so around my town because it has a hurrendous vaccum and the carb is rich like bill gates. so my question is, how will the 455, i'll probably set it up to mild performance (i.e. stock valvetrain, maybe a mild mild performance cam, headers, highrise intake) effect my gas milage. this is in comparison to my other option, a new 350 which i would probably trick out with all the goodies that i could find to make it move the big girl. the rear end gears are high...i think i read somewhere that they were like 240 something! this could be inaccurate though, and any info on that would be helpful also. ill probably also still be running th350 with the 455. any numbers, or experience with my dilema would be greatly appreciated, as this is and will be my daily driver, and gas is a pretty big concern. thanks~charlie
well i have a 72 buick skylark with a stock 455 in it, fresh rebuild with stock 2.56 gears out back and a th350 tranny....i have electric fans, i just got a tune up and i'm getting around 13mpg around town and somewhere around 16-19mpg on the highway....i'm hoping with better gears and an overdrive tranny, better carb and some head work that i can pull better than that... hope that helps yah daniel duncan
My '69 Sky with low compression 350-2 barrel, 3.23 geared in good tune never got above 14mpg on the highway.....while my snarlin' 463" in the GS and 3.42's would routinely knock down 15-16 mpg. Haven't yet measured it with the 3.08's in it now. .....and the GS is approx. 400 pounds heavier When you install a 455" you change your measuring criteria from Miles per Gallon to Smiles per gallon :TU: :Smarty: :TU:
Economy? This is a direct quote from the '65 big car "Owners Guide": ECONOMY NOTE Buick owners have a choice of good performance with economy or superb performance. Good fuel economy may be obtained by making normal starts and not attempting maximum acceleration at all times. If, however, you desire maximum performance on every start, you must expect less fuel economy. :TU:
The 455 in my 37 Buick coupe ( street rod) gets 16-18 MPG on the highway and 12-14 MPG in city driving. It has a 2.56 axle and weighs 3750. My 72 GS convert has a 3.31 axle and a 200-4R and is comparable for mileage, but has a bigger cam and headers. It weighs 3990 empty.
